As one type of a vehicle brake device, a device which is disclosed in a Patent Literature 1 is known. As shown in FIG. 1 of the Patent Literature 1, the vehicle brake device includes a master cylinder 1 wherein master pistons 113 and 114 are driven to move by a servo pressure in a servo chamber 127 and by the movement of the master pistons, master pressure in the master chambers 132 and 136 changes, a high pressure source 431 and a mechanical type servo pressure generating device 44 connected to a high pressure source 431 and the servo chamber to generate the servo pressure in the servo chamber corresponding to the pilot pressure generated in a pilot chamber based on the brake hydraulic pressure of the high pressure source, an electric pilot pressure generating device 41, 42, 43 connected to the pilot chamber for generating a desired pilot pressure in the pilot chamber, a master-pilot connecting brake fluid passage 511 which connects the master chamber and the pilot chamber and a brake actuator 53 which performs an ABS control and an ESC control and so on. The master-pilot connecting brake fluid passage is a passage branched from the master-wheel connecting passage 51 which connects the master chamber and the wheel cylinder 541, etc. The vehicle brake device includes a pressure sensor 74 which detects the servo pressure.
In a vehicle brake device as structured above, when a brake pedal 115 is depressed, the brake ECU 6 controls the pressure decreasing valve 41 and the pressure increasing valve 42 in response to the information from the stroke sensor 72. In other words, generally, a target servo pressure is set which corresponds to the stroke amount of the brake pedal 115 and then the pressure decreasing valve 41 and the pressure increasing valve 42 are controlled so that the target servo pressure and the actually detected servo pressure (actual servo pressure) agree with each other (feed-back control).